Metal working

ABSTRACT

This invention relates to methods of working workpieces to improve their characteristics. The invention provides causing a bulge to be formed in the workpiece and to be moved along the workpiece for any desired number of times. The invention is most applicable to methods of rolling processes.

United States Patent Marcovitch [151 3,656,332 [4511 Apr. 18, 1972 [54]METAL WORKING [72] Inventor: Jacob Marcovitch, Johannesburg, Republic ofSouth Africa Rotary Profile Anstalt, Vaduz, Liechtenstein 22 Filed: May22,1969 21 App1.No.: 826,816

[73] Assignee:

[58] Field of Search ..72/366, 76, 198, 102, 103, 72/104, 107, 108, 100,77, 80-84 [56] References Cited UNITED STATES PATENTS 432,463 7/1890White ..72/l03 1,141,425 6/1915 Simpkins ..72/103 1,629,759 5/1927 Wise..72/89 1,767,896 6/1930 Roeckner .....72/366 1,930,562 10/ 1933 Krueger..72/107 2,945,530 7/1960 Maust ..72/ 366 3,047,046 7/1962 Nilsson ..72/l 00 3,138,982 6/ 1964 Sporck ..72/366 3,230,606 l/l966 Saito et al....72/108 3,459,027 8/1969 Brownsteln ....72/366 3,036,622 5/1962 Hitz..72/366 FOREIGN PATENTS OR APPLICATIONS 1,020,950 12/1957 Germany..72/366 Primary Examiner-Richard .I. Herbst Attorney-Young & Thompson[57] ABSTRACT This invention relates to methods of working workpieces toimprove their characteristics. The invention provides causing a bulge tobe formed in the workpiece and to be moved along the workpiece for anydesired number of times. The invention is most applicable to methods ofrolling processes.

4 Claims, 9 Drawing Figures PATENTEBAPR 18 1912 SHEET 1 UF 3 c/ncoaM/mco w ray By 7* (JMIQTTYS.

PATENTEDAPR 18 m2 SHEET 2 OF 3 /n C06 Mmwa V/TC'H PATENTEBAPR 181972 3,656, 332 sum 3 BF 3 #4 gif- Ame-Wm:

Jqcoe Ma/eco wrcH BVM METAL WORKING This invention relates to methods ofworking materials, especially metals, from the surface.

It is known that during the working of metal for example by rolling orforging, the metals acquire certain advantageous characteristics. Theextent of the working of the metal is how ever determined by the amountof reduction of the workpiece that is required. In other words theamount of working is determined by the initial dimensions of theworkpiece and its final dimensions. It has not been possible hitherto toprovide a greater amount of surface working than is possible within thelimits set by these initial and final dimensions. It is an object ofthis invention to provide a method which enables any desired amount ofsurface working to take place without final reduction of the workpiecebeyond a predetermined thickness.

According to one aspect of this invention there is provided a method ofworking a workpiece by forming a bulge in the workpiece and moving thebulge along the workpiece. This working may be associated with a formingoperation by rolling and may be carried on further after the workpiecehas been fully formed with a bulge still persisting and thereafterretracting the rollers to disperse the bulge.

Embodiments of this invention will now be described with reference tothe accompanying drawings.

In the drawings:

FIG. 1 is a sketch illustrating how the invention is applied to anelongated workpiece.

FIG. 2 shews an end view of a type of apparatus for working an elongatedworkpiece.

FIG. 3 is a side view of one apparatus of the type of FIG. 2.

FIG. 4 is a view similar to FIG. 3 of alternative apparatus for workinga workpiece in accordance with the invention.

FIG. 5 is a sketch diagrammatically shewing how a relatively flatworkpiece may be worked in accordance with the invention.

FIG. 6 is a section through apparatus for use in working a ring from aside in accordance with the invention FIG. 7 is a side view through theworkpiece of FIG. 6 showing how the workpiece material reacts duringrolling.

FIG. 8 is a section through apparatus used in working a ring from theinside and FIG. 9 is a section on line 9 9 ofFIG. 8.

Referring now to FIG. 1 there is shown a billet in the form of acylindrical rod 10 of the desired final diameter. A bulge 12 is formedin the rod 10. In the method of the invention, the bulge I2 is made totravel in ripple fashion, or in the manner of wave action, along thelength of the billet. Two of the positions which the bulge will occupyare indicated in dotted lines at 14 and 16. The process is repeatedseveral times up and down the length of the billet, as indicated by thearrow 15. Axial pressure is preferably applied to the billet during theoperation to maintain it in a state of compression. Care must be takenthat the bulge is not rolled out at the ends of the rod until treatmenthas been completed. The ends of the rod will therefore not be as fullytreated as the remainder of the rod.

It is obvious that, with movement of the bulge, the metal in the zonemomentarily occupied by the bulge will be displaced both radially andaxially relatively to the position it occupied before the arrival of thebulge, and after its departure. This applies to the entire body of themetal in the bulge, except perhaps theoretically at the billet axis. Themetal is thus worked substantially throughout its mass. The ends of therod being not fully rolled will be removed from the rod by parting inany conventional manner.

This surface working process will normally take place with a heatedworkpiece, the heating being as in conventional processes, i.e. forAusforming, the workpiece may be in the 1,000 F. range and forMarforming in the 500 F. range, but it may be heated to any desiredtemperature to give the desired properties or it may be carried out atambient conditions.

FIG. 2 shews a general form of apparatus for use in carrying out theprocess described above. The apparatus comprises three rolls 18,20 and22 equispaced around a billet 24. These rolls work the billet 24 as itpasses in the direction of its axis through the throat defined betweenthe rolls 18,20 and 22. The rolls are supported and driven by means (notshewn) but which are known to those skilled in this art.

The operative part of one suitable machine of the general type of FIG. 2is shewn in FIG. 3. The rolls 18, 20' and 22' have identical diametercylindrical inlet and outlet portions 26 and 28 and between theseportions 26 and 28 helical scrolled surfaces 30. The crests of thescrolls lie on the projection of the cylindrical portions 26 and 28. Thebases of the scrolls are arranged so that the scroll is concave and hasa nipped waist. In this embodiment the rolls are arranged with theiraxes 32 parallel to each other and to the billet axis 34. The scrollsare in register where they engage the billet 24 so producing annulargrooves and ridges in the billet 24' As the rolls have nipped waists,they define a generally bulged zone along their lengths in which thebillet 24 is adapted to be confined. The pitch of the scrolls is suchthat the axial speed of the billet 24, as it is drawn through the spacebetween the rollers in the direction of the arrow 36, tends to beslightly retarded in the outgoing portion of the bulge relative to theincoming portion. There can never be any accumulation of material in thebulge, but establishing this tendency ensures that the space for thebulge is always full. The crests of the scrolls keep the material of thebillet in axial compression at the bulged zone. The pitch of the scrolls30 may decrease towards the center of the scroll from both ends.

The billet is formed initially with a bulged zone which is inserted inthe throat space between the rollers; and, with correct feed and drivingarrangements, the bulge persists but ripples relatively along the lengthof the billet as the operation proceeds.

After the billet has almost completed a path through the machine, sothat the bulge is not rolled out of the billet, the billet is reinsertedfor a second pass in which the bulge is moved in the reverse directionalong the length of the workpiece. More passes may follow depending onthe extent of working required.

For the reasons as discussed above there is a high degree of containmentof the workpiece in the bulged zone, so that the metal in that zone isin a state of extreme compression. Great care must therefore beexercised in the design and construction of the components that operateon the billet to ensure that there is no permanent elastic deformationin those components and yet that the billet is readily inserted andremoved. Massive backing for the rolls may be necessary to allow themachines to withstand the large forces generated. Thus the rolls 18, 20and 22 in FIG. 3 will ordinarily not be set in bearings but will besupported along their full length on surfaces that are themselvesmassively supported.

Another embodiment with three rolls 18", 20" and 22 having skewed axes32 and identical diameter inlet and outlet cylindrical sections 26 and28 and between them nipped waists to define a bulged zone is shewn inFIG. 4. In this case the rolls are provided with annular portions 38that are out of register, so generating a helical scroll on the billet.As shewn in the lower roll, the scroll is made up of individually drivenand mounted sections, 40a, 4012, etc., connected to a common drivenshaft 44 by individual gearing transmissions schematically indicated at42a, 42b, etc. The other two rolls are similarly compounded of sections.

The driving arrangements are such that, on theinsertion of a suitablybulged end of a billet 24'. into the space between the rolls, driving ofthe rolls 18'', 20" and 22" will cause the scrolled profile to beimpressed on the billet, which propels itself through the machine whilethe bulged zone moves relatively along it, the metal in that zonereceiving a severe kneading. The movement of the bulge is aided by aspeed differential in the roll sections to the left of the waist of therolls, and a corresponding reverse differential to the right of thewaist. Thus the billet enters and emerges from the machine with auniform diameter, its helical scrolled bulged zone existing only in theregion of the waist of the rolls. Here again the starting billet may beof the desired final diameter and the crests of the annular portionsbite into the material of the billet bulge. Axial input pressure may beprovided acting on the ends of workpiece.

The embodiments described above might easily be modified to treattubular workpieces, either by the insertion of a solid mandrel in thetubular cavity, or of a mandrel on which are mounted rollers withpropagate the ripple-like movement of the bulge as the billet is drawnover the mandrel acting against a cylindrical die on the outside, withend entrapment for the billet.

Flat or relatively fiat workpieces can also be worked in accordance withthe invention. Reference is now made to FIG. 5 in which a slightly bowedworkpiece 52 is shewn in position in a correspondingly shaped recess 54in a die 56. A main pressure roller 58 is flanked by two side rollers 60which prevent excessive bowing of the workpiece during rolling. Theworkpiece 52 which may be heated to the temperature ranges mentionedabove is rolled down to fill the die and additional pressure is thenapplied to the main roller 58 and a bulge 62 is maintained. The mainroller 58 then moves the bulge 62 from one end of the workpiece 52 tothe other. The ends of the recess 54 prevent axial elongation of theworkpiece 52. As the roller 58 must be lifted over the bulge to commencerolling it in the opposite direction, it will be apparant that theentire length of the workpiece 52 will not be worked by the main roller58 and it will be necessary for the ends of the workpiece to be cut offbefore the workpiece is to be used. It will be noted that the ends ofthe recess 54 prevent elongation of the workpiece in the direction ofrolling. When the workpiece 52 is sufficiently worked, the pressure ofthe main roller 58 is slackened off and rolling is continued until theworkpiece is rolled to its desired thickness and the bulge 62disappears. If desired the workpiece may be taken from the recess 54,turned over and re-rolled. In this way both sides of the workpiece 52will be worked according to the invention. The bowed workpiece may befurther rolled over a flat platten (not shewn) so that a flat member isproduced.

Reference is now made to FIGS. 6 and 7 wherein is shewn apparatusworking the sides 60 of a ring 62 which sides are of course endless. Theworkpiece 62 which is to be produced to the desired final dimensions andproperties is inserted into a recess 64 in a die 66. A series of conicalrollers 68 now roll over the upper side 60 of the ring 62, so as to fillthe die and to work the piece further by the formation of a bulge 70 andmoving this bulge 70 around the surface of the side 60. When sufficientworking of the workpiece has taken place the pressure of the conicalroller 68 is taken off and rolling continued until the workpiece returnsto the desired final diameter and the material of the bulge is absorbedin the material of the ring. The temperature at which this operationtakes place is as discussed above. It will be noted that as theworkpiece is forced into the die recess, the material of the workpiecewill be under lateral pressure throughout and at the roller, thematerial of the workpiece will be wholly contained by the sides of therecess and the roller. No circumferential elongation of the workpiecetakes place during this operation In FIGS. 8 and 9 there is shewn aset-up for treating an endless bearing race 72 especially its innersurface The apparatus comprises a pressure roll 74, and anvil ring 76, amandrel 78 and two pairs of back-up rolls 80 on which the cylindricalcontinuations 82 of the mandrel 78 respectively roll. The mandrel 78 hastwo upstanding enlarged diameter cylindrical collars 84 between whichthe workpiece 72 is trapped The workpiece 72 is rolled to size betweenthe anvil ring 76 and the mandrel 78. Further pressure is then appliedto cause the formation of the small bulge 86 and rolling continues whilethis bulge 86 moves along the entire inner surface of the workpiece 76.When sufficient working had taken place, the pressure exerted by themandrel 78 is allowed to slacken off so that the workpiece is allowed toreturn to its desired dimen sions and the bulge is rolled out of theworkpiece.

Here again the temperature of the workpiece during the surface treatmentis as discussed above.

I have found that In the ways mentioned above I can provide a suitablytreated workpiece the working of which is not limited to the reductionin thickness of the workpiece.

The invention is not limited to the precise details hereinbeforedescribed and illustrated. For example, the workpiece may be movedaxially when rolling as described with reference to FIG. 5 after eachpass so that a relatively wide workpiece may be treated in accordancewith this invention.

Iclaim:

1. A method of working the surface of an elongated metal workpiecehaving a predetermined initial thickness which is uniform along thelength of said workpiece, comprising deforming a surface of theworkpiece beyond its elastic limit to form a bulge therein, and movingsaid bulge lengthwise along said workpiece a plurality of times so thatsaid bulge passes a given point on said workpiece a plurality of times,and then removing said bulge to restore said workpiece to saidpredetermined thickness.

2. A method as claimed in claim 1, in which said workpiece is straightand said bulge reciprocates lengthwise along said workpiece.

3. A method as claimed in claim 1, in which said workpiece is annularand said bulge moves in a plurality of circuits about said workpiece.

4. A method as claimed in claim 1, in which said bulge is moved bypassing said workpiece between rollers, and said bulge is removed byincreasing the distance between the rollers so as to roll the materialof the bulge back into the workpiece.

1. A method of working the surface of an elongated metal workpiecehaving a predetermined initial thickness which is uniform along thelength of said workpiece, comprising deforming a surface of theworkpiece beyond its elastic limit to form a bulge therein, and movingsaid bulge lengthwise along said workpiece a plurality of times so thatsaid bulge passes a given point on said workpiece a plurality of times,and then removing said bulge to restore said workpiece to saidpredetermined thickness.
 2. A method as claimed in claim 1, in whichsaid workpiece is straight and said bulge reciprocates lengthwise alongsaid workpiece.
 3. A method as claimed in claim 1, in which saidworkpiece is annular and said bulge moves in a plurality of circuitsabout said workpiece.
 4. A method as claimed in claim 1, in which saidbulge is moved by passing said workpiece between rollers, and said bulgeis removed by increasing the distance between the rollers so as to rollthe material of the bulge back into the workpiece.